Texas Instruments TI-86 (Engineering Sample)

Date of introduction:  January 6, 1997
 Available: May 1997
Display technology:  LCD dot matrix
New price:  $150.00  Display size:  8 * 21 characters
Size:  7.2" x 3.2" x 0.80"
 182 x 81 x 20 mm3
Weight:  5.9 ounces, 165 grams Serial No:  
Batteries:  4*AAA + CR1620 (35mA) Date of manufacture:  mth 02 year 1997
AC-Adapter:   Origin of manufacture:  Taiwan (I)
Precision:  14 Integrated circuits:  CPU: Toshiba T6A43
 ROM: AT29C020
 RAM: SRM20100
 Display: T6A40,
Program steps:  96k Bytes Courtesy of:  Joerg Woerner

The TI-86 added more functions and memory to the it's predecessor TI-85 and carried the new, smoother housing.

The main features of the TI-86 in a short summary:

Graphing of up to 99 functions at one time.
Parametric graphing to analyze up to three parametric equations.
Manipulation of matrices with dimensions of 80*80.
One- and two-variable statistical analyses with up to 6,000 data points.
Programs with a total of 96,000 Bytes.

Disassembling this TI-86 Engineering Sample manufactured in February 1997 reveals no big surprises. It makes use of just 5 main components on the printed circuit boards (PCB’s):

CPU (Central processing Unit): The Toshiba T6A43 is a so-called Application Specific CPU and combines a Z80 core with an ASIC (Application Specific Integrated Circuit). You’ll find different approaches within the graphing calculator line of Texas Instruments, sometimes the use of an individual CPU (e.g. Z80 and M68000) with a supporting ASIC or – like with this TI-86 the integration of the CPU into the ASIC.

ROM (Read Only Memory): The ROM contains the operating system of the calculator. The first products on the market used mask-programmable ROMs, the program was stored already during the production of the Integrated Circuit. Later calculators changed to Flash ROM, a technology allowing the programming of the software during the final production stage of the calculator. With the TI-83 Plus and all later graphing calculators from Texas Instruments even the user was able to reprogram the operating system. 

This TI-86 manufactured early in 1997 makes use of a Flash ROM ATMEL AT29C020 in a socket for convenient replacement. Later TI-86 calculators host either a one-time programmable (OTP) ROM AT27C020 or a Mask ROM LH532©98 manufactured by Sharp, Japan. It is common practice in software engineering to avoid the high one-time costs and long lead time of a Mask-ROM during the ramp up of a new product. OTP ROM like the AT27C020 are on the other hand more expensive.

RAM (Random Access Memory): The RAM is used as data memory and is used to store both variables, user programs and intermediate results. This TI-86 makes use of SRM20100 chip manufactured by Epson, Japan. The capacity of the memory is 128k Bytes.

DISPLAY: The Toshiba T6A23 is a column driver for small-to-medium-sized dot matrix graphic LCDs, while the T6A40 is a row driver. They are compatible with Z80 based CPUs and drive displays with up to 128 columns, resp. 64 rows. The display size of the TI-86 is 128 * 64 pixel, therefore one display driver each is necessary.

A special "teacher version" called TI-86 VSC combines the standard TI-86 features with a port to connect to a ViewScreen panel via a cable. Placing the panel on the overhead projector enlarges the image of the handheld screen so that each student can follow along.

A serial port of the calculators allows the connection to the Calculator-Based Laboratory system CBL, its successor CBL 2, the Calculator-Based Ranger CBR and its successor CBR 2.

Don't miss the colorful slide cases developed for the TI-83 Plus, they fit on the TI-86, too.

Don't miss the TI-89, a pocket sized Symbolic calculator.


TI-86_ES_OS.jpg (41774 Byte)1.2

You can check the ROM version of your TI-86 using the following key sequence and reading the number on your screen:

[2nd] [MODE] [ALPHA] [S]

Information provided by and Xavier Andréani.

Exam acceptance:

The TI-86 is permitted (as of September 27, 2007) for use on SAT, ACT, PSAT and AP exams.

Obsolete / Discontinued Products:

The TI-86 Graphing Calculator has been discontinued (as of June 8, 2008) and is no longer available at most retail locations. 

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If you have additions to the above article please email:

© Joerg Woerner, February 23, 2009. No reprints without written permission.